For starters ... it depends on where you are. Swampy land means bugs at any hour. And the worst bug attack I ever experienced was black flies at midday.
Also... "may" is a weasel word.
Avoiding repellents on your face: This, again, is someone who has not faced serious bug density.
OK, I grant, bug veils and such may be a better answer, as may permethrin-coated clothing (vs. repellent applied to skin). Fact remains: A product which stays on the shelf does even less good, and I will use the combined when I won't use the others.
There aren't many bugs on a typical beach, so if that's your idea of vacation maybe this is good advice. For camping, hiking, or simply working outdoors, I know what works for me.